COMPRESSIVE STRENGTH CHARACTERISTICS OF CONCRETE …

CSID Journal of Infrastructure Development, 4(1): 112-121 (2021) ISSN 2407-4438

COMPRESSIVE STRENGTH CHARACTERISTICS OF CONCRETE MODIFIED

WITH TREATED HIGH-DENSITY POLYETHYLENE

Iorwuese Anum1*, Olorunmeye Fredrick Job2

1Department of Building, Modibbo Adama University, Yola, P.M.B. 2076, 640001 Adamawa State,

Nigeria 2Department of Building, University of Jos, P.M.B. 2084, 930001 Plateau State, Nigeria

(Received: March 2021 / Revised: March 2021 / Accepted: May 2021)

ABSTRACT

Waste plastic materials are typical wastes of interest to researchers and are arguably the most

common forms of waste, especially in African cities. The reuse of plastic waste in concrete

matrices has the potentials to contribute to the development of sustainable concrete likely to

conserve resources and prevent pollution. However, the inclusion of plastics in concrete has

been reported to have a negative impact on its compressive strength behaviour. This research is

aimed at ameliorating this negative impact through pulverisation and chemical treatment of

High-Density Polyethylene (HDPE) before its use as an admixture for concrete production.

Concretes of Grades M25 and M50 were prepared using (150 x150 x 150) mm steel moulds,

adopting the BRE mix design method. The concrete mix was modified with pulverised High-

Density Polyethylene (HDPE) treated with 20% hydrogen peroxide at (0, 0.25, 0.5, 0.75, and

1%) by weight of cement. Hydroplast-500, a superplasticizer was used throughout the study in

order of 1000litres/50kg by weight of cement. A constant water/cement ratio of 0.4 and 0.36

was adopted for requisite workability for Grades M25 and M50 concretes respectively. After 7,

28, and 90 days of curing in water, the concrete cubes were dried and tested for their

compressive strengths. Results obtained showed that at HDPE content beyond 0.5%, restrained

hydration takes negative effects on the concrete. It was also shown that the designed

compressive strengths of the tested samples were satisfactorily met in all cases indicating

improvement in the compressive behaviour of the samples. Based on the findings of this study,

it was recommended that treated pulverised HDPE could be used as an admixture in concretes

without compromising their compressive strengths.

Keywords: Chemical Treatment; Compressive Strength; High-Density Polyethylene; Modified

Concrete; Pulverisation.

1. INTRODUCTION

It is universally acknowledged that concrete is the most widely and conventionally used

construction material worldwide as a result of its versatility, strength, durability, ease of use,

and contribution to social progress, economic growth, and environmental protection (Paul,

2016; The Guardian, 2019). The extensive usage of concrete in construction according to

Lafarge Holcim (2019) justifies why this conventional material is being continuously modified

and developed to perform better in many situations. *Corresponding author’s email: [email protected], [email protected] Tel. +234-8036094154 DOI: https://doi.org/10.32783/csid-jid.v4i1.201

mailto:[email protected]

mailto:[email protected]

Anum and Job 113

According to Rutkowska et al. (2020), concrete has proven to be excellent disposal means for

fly ash, silica fume, ground granulated blast furnace slag, and marble powder which can trap

hazardous materials and also enhance the properties of concrete. Interestingly, the global

construction industry consumes an estimated 20 billion tons of concrete every year and this

large annual production of concrete consequently leads to an equally large estimated

consumption of component materials of about 15 billion tons of aggregates and 4.2 billion tons

of cement (Tosic et al., 2017). Taking into account the huge volume of concrete produced

annually, the concrete industry is unquestionably one of the ideal mediums for the economic

and safe use of millions of post-consumer waste plastics (Sandanayake et al., 2020).

Currently, global plastic production exceeded 311 million metric tons from 2.5 billion metric

tons of solid waste generated in 192 countries (Bokani, 2019). A separate study by Statista

(2021) revealed an estimated global plastic production of 368 million metric tons per year. In

Nigeria for instance, the per capita consumption of plastics has grown by about 5% annually

over the past ten years, from 4.0 kg in 2007 to 6.5 kg in 2017, and is estimated to be 7.5 kg in

2020 (Bokani, 2019). This fast growth is attributed to the boost in industrialization and the

rapid improvement in standards of living (Babafemi et al., 2018). Averill and Eldredge (2016)

further adduced reasons for the phenomenal increase in the usage of plastics to its low density,

strength, user-friendly designs, fabrication capabilities, lightweight, long life, and low cost.

Therefore, plastic materials are typical waste materials of interest and are arguably the most

common forms of waste in African cities (Smallstarter, n.d.).

Polyethylene according to Statista (2021) is the world’s biggest and most popular tonnage

plastic prepared by the catalytic polymerization of ethylene. High-Density Polyethylene

(HDPE) which is defined by the density of greater or equal to 0.941g/cm3 accounts for 46% of

total polyethylene production globally (Plasticsinsight.com, n.d.). High-Density Polyethylene

possesses special properties such as increased resistance to permeability, good chemical

resistance, high rigidity, high toughness and flexibility, improved heat resistance, good impact

resistance, and lightweight which makes it a material of choice for many engineering

applications (Dorigato et al., 2012; Plasticsinsight.com, n.d.).

Pulverised HDPE may be defined as plastics of HDPE parent materials that have been

reclaimed, sorted, and reduced to smaller particles by grinding to create a new material with

smaller particle sizes and improved surface area (Plasticsinsight.com, n.d.). Therefore,

pulverised high-density polyethylene concrete is a composite material consisting of a cement-

based matrix with ordered or randomly distributed particles of high-density polyethylene

material as admixtures.

The compressive strength of concrete generally is its ability to resist compressive forces which

is a force tending to compress or squeeze it together. The compressive strength of concrete is

one of the most considered quantitative parameters because of its requirement when designing

structural concrete elements (Slaiai, 2017).

A study by Naik, et al. (1996) has investigated the effects of post-consumer plastics in concrete

and found that the inclusion of plastic fibers in concrete increases its ductility while improving

fracture resistance, though with a negative impact on compressive strength and creep behaviour.

This phenomenon according to the authors is because ordinary Portland cement concrete

reinforced with plastics is liable to poor bonding due to the lack of chemical bond that exists

between the materials. Studies by Lu et al. (1998) and Ebnesajjad (2011) have suggested that

poor bonding between concrete and plastic materials may be improved by physical processing

or chemical treatment of plastics prior to mixing. These techniques, according to these studies,

have a good promise of improved bonding of plastics to cementitious materials as a result of

bonding likely to develop with the surrounding matrix, which may result in higher strength. In

114 Compressive Strength Characteristics of Concrete Modified With Treated High-Density Polyethylene

light of all these arguments, this research is premised on ameliorating the negative impact of

poor bonding between plastic based materials and concrete by pulverisation and chemical

treating of High-Density Polyethylene (HDPE) before its use as an admixture for concrete

production.

2. LITERATURE REVIEW

The compressive strength of concrete generally is its ability to resist compressive forces which

is a force tending to compress or squeeze it together. The compressive strength of concrete is

one of the most considered quantitative parameters because of its requirement when designing

structural concrete elements (Slaiai, 2017). The compressive strength of plastic concretes

depend on many parameters such as the water/cement ratio, constitution level of the plastic

materials (mostly aggregates), and the type and shape of the waste plastic (Akçaözoǧlu et al.,

2010; Albano et al., 2009; Asokan et al., 2009; Babafemi et al., 2018). The mechanical

properties of concrete containing recycled PET were identified by Cordoba et al. (2013) to

depend on the particle size with the highest compressive strength obtained with the smallest

sizes of PET (0.5mm). The study also established the fact that mechanical properties of plastic

concrete such as compressive strength increases with a reduced particle size of plastics and with

lower concentrations of the plastic content. The lower sizes and concentrations of plastic

particles create fewer spaces in the concrete, and in consequence, strength is increased (Ávila

Córdoba et al., 2013). The compressive strength of plastic shreds in concrete was studied by

Naik, et al. (1996). The study reported a compressive strength decrease with an increase in the

amount of plastic in concrete, particularly above 0.5% plastic addition.

Patil et al. (2014) reported that the modified concrete mix, with the addition of plastic aggregate

replacing conventional aggregate up to a certain 20% gives strength within the permissible limit

but decreased compressive strength when plastic was replaced with coarse aggregate. Besides,

Raghatate and Polytechnic (2012) reported that there is about a 20% reduction in compressive

strength at 28 days of curing using the plastic pieces in concrete. In each case reported,

compressive strength reduction was a result of improper bonding between organic plastic

materials and inorganic cementitious materials.

Gu and Ozbakkaloglu (2016), attributed the reduction in compressive strength to one or a

combination of the following: the elastic modulus of the plastic aggregates/filler aggregates

being lower than the natural concrete aggregate, the low bond strength between the surface of

the plastic aggregate/filler and the cement paste, the restrained cement hydration reaction near

the surface of the plastic resulting from the hydrophilic nature of the plastics or the high air

content and porosity of the plastic concrete. The use of recycled plastic fibers with a high

ultimate tensile strength and smaller fiber content results in a more significant improvement in

compressive strength than fibers with low compressive strength. Also, straight fibers increased

compressive strength more than those with embossed geometry (Fraternali et al., 2014).

Additionally, the compressive strength of plastic concrete was increased with the injection of

plasticiser (Rai et al., 2012).

It can be seen that the compressive strength of plastic concrete is likely to be increased

substantially without compromising its performance if plastic particles are further processed or

treated to improve the bonding of the composites in a superplasticised environment. The

pulverization of the polyethylene into a powder is presumed to reduce their particle sizes, hence

expected to increase the compressive strength. The limitations of most previous research

attempts on the use of plastics in concrete were the fact that plastic used presented wider

surface areas (which likely inhibited hydration of cement) or was not treated (which may have

affected the bonding to cementing materials).

Anum and Job 115

3. METHODS

3.1. Materials

The materials used in this research are: ‘BUA’ (42.5R grade) brand of Ordinary Portland

Cement conforming to ASTM C 150 (2015). Pulverised High-Density Polyethylene was

sourced from landfills in Jimeta, Yola North Local Government Area of Adamawa State,

Nigeria. The High-Density Polyethylene (HDPE) were first sorted, cleaned, washed, and

mechanically pulverised into smaller particles passing a 2mm British Standard (BS) sieve and

chemically treated with 20% hydrogen peroxide to make the particles hydrophilic. Sieve

analysis was then performed on the pulverised High-Density Polyethylene after taking the

samples to approximately Saturated Surface Dry (SSD) condition as shown in Figure 1.

Figure 1 Pulverised and Sieved High-Density Polyethylene

Hydroplast - 500 conforming to ASTM C 494 (2015) was procured at Armosil West Africa

Garki, Abuja, and used as a superplasticiser. Good quality Zone I river sand passing through

4.75mm BS sieve sourced from Jere town in Kagarko Local Government Area of Kaduna State

was used.

Table 1 Properties of Materials Used

Properties Cement HDPE Fine

Aggregate

Coarse

Aggregate

Hydroplast-

500

Specific Gravity 3.15 1.03 2.66 2.62 1.175

Standard Consistency 30% - - - -

Initial Setting Time (min) 60 - - - -

Final Setting Time (min) 320 - - - -

Bulk Density(Kg/m3) 1440 - - - -

Compressive Strength at 3

Days (N/mm2)

11.3 - - - -


Days(N/mm2)

25 - - - -


Days(N/mm2)

46 - - - -

Moisture Content (%) - 0.55 0.13 0.2 -

Water Absorption (%)

Appearance

-

Grey

0.067

Ash-

grey

0.38

-

0.29

-

-

Dark brown

The suitability of the sand for the intended use was ascertained in the laboratory in accordance

with the provisions of BS EN 12620 (2013). 20mm nominal sizes natural machined crushed

rock sourced at Dutse Alhaji, Abuja and potable water obtained from Nigerian Building and

Road Research institute laboratory, supplied by the Federal Capital Territory Water Board was

used. This water was used throughout this research work both for mixing as well as curing of


the concrete and in accordance with the provisions of ASTM C1602/C1602M (2012). The

properties of the materials are presented in Table 1.

3.2. Methods

The high-density polyethylene was collected, sorted, cleaned, washed, and pulverised into

smaller particles using a locally fabricated pulverizing machine. The High-Density

Polyethylene powder was then subjected to pretreatment by immersing it in a 20% solution of

hydrogen peroxide for 20 minutes and then sun-dried to saturated surface dry condition. Figure

2(a) and 2(b) shows the Scanning Electron Microscopy (SEM) images of the treated and

untreated Pulverised HDPE. The concrete specimens were prepared at the Materials and

Concrete Laboratory, Nigerian Building and Road Research Institute (NIBRRI) headquarters

Abuja, Nigeria using (150 x 150 x150) mm steel moulds. The cubes were prepared in

accordance with the provisions of BS EN 12390-3 (2002). Concrete mixes were prepared using

the BRE method of mix design. Table 2 shows the number of materials required per cubic

meter of concrete as computed by the mix design. The investigation was carried out on Grade

25 and Grade 50 concretes representing medium-strength concretes (Grade 25) and high

strengths (Grade 50) concretes respectively.

The samples were prepared with the pulverised and treated HDPE of fine consistency, precisely

those passing through 2.00mm BS sieve, and added in percentages of (0, 0.25, 0.5, 0.75, and 1)

by weight of cement. Dosages of hydroplast-500 in order of 1000litres/ 50kg by weight of

cement was used throughout the study as recommended by the manufacturers to enhance the

workability of the matrix.

Figure 2(a) SEM image of Untreated

Pulverised HDPE (X10, 000 Magnification)

Figure 2(b) SEM Image of Treated Pulverised

HDPE (X1, 500 Magnification)

A constant water/cement ratio of 0.4 and 0.36 for requisite workability was adopted for Grades

25 and Grades 50 concretes respectively after trial mixes.

The fresh concrete was cast into the appropriate moulds (Figure 3) and vibrated for at least 25

seconds in accordance with ASTM C 192/ C192M (2016) using an electrically operated small

size poker vibrator. After 24 hours of casting, the concrete beams were demoulded, weighed,

and completely cured in water tanks. The compressive strength tests were carried out on the

150 x 150 x150 mm hardened concrete cubes after curing for 7, 28, and 90 days and in

accordance with BS EN 12390-3 (2002) using a universal testing machine as shown in Figure 4.

Anum and Job 117

Table 2 Quantity of Ingredients Required (kg) Per Cubic Metre of Concrete

Concrete Grades

Ingredient (Kg) C25 C50

Cement 360 430

Fine Aggregate 630 570

Coarse Aggregate 1330 1330

Water 145 155

Hydroplast-500 7.2 8.6

Pulverized HDPE

0.0% 0 0

0.25% 0.90 1.08

0.50% 1.80 2.15

0.75% 2.70 3.25

1.0% 3.60 4.30

Figure 3 Concrete Cubes Cast with (150 X 150) mm Steel Moulds

The average failure loads were used in obtaining the compressive strength, using the

relationship in equation (2).

…………………………………………………… (2)

Where: = Compressive Strength (N/mm2)

= Magnitude of the Load at Failure (N)

= Cross-sectional Area of the Cube Specimen (mm2)


Figure 4 Determination of Compressive Strength of Cubes Using Universal Testing Machine

4. RESULTS AND DISCUSSION

Figures 5 (a) and 5(b) show the relationship between compressive strength development and

hydration periods of 7, 28, and 90 days for grades M25 and M50 concrete respectively. A

critical analysis further revealed that the compressive strength of all concrete specimens

increased with curing age compared on the basis of 90 days indicating that no noticeable

degradation of the concrete occurred within the 90 days test. Compressive strength however

decreased with the inclusion of pulverised HDPE with the least reduction of 19.09%

(29.67N/mm2) for Grade M25 while 16.04% (45.32N/mm2) was recorded as the least reduction

for Grade M50 concretes in all cases at 0.5% HDPE by weight of cement. This implies that 0.5

% HDPE content is the optimum content beyond which restrained hydration takes negative

effects on the concrete. The reduction in compressive strength could be attributed to the

restrained cement hydration reaction near the surface of the HDPE resulting from their

hydrophilic nature.

The compressive strength of the control mixes was observed to be higher than that of all mixes

containing pulverised HDPE. However, a minimum strength of 14.35N/mm2 and 25.05N/mm2

was obtained for Grade M25 concretes at 7 and 28 days of curing while a minimum of

33N/mm2 and 50N/mm2 was obtained for Grade M50 concretes at 7 and 28 days of curing

respectively. These values correspond to the minimum expected designed strength of 65% at

7days of curing and 99% strength at 28 days of curing in water suggesting that the designed

strength was satisfactorily met in all cases. This finding is considered as an improvement over

the previous findings (Atul & Polytechnic, 2012; Gu & Ozbakkaloglu, 2016; Naik et al., 1996),

who observed the same trend of strength reduction of the modified concrete with plastic

materials. The improved performance in this study could be probably attributed to the reduction

in the particle sizes of the HDPE via pulverisation as well as increased coverage of the polymer

surface with R–OH and R– COOH sites produced by the oxidizing hydrogen peroxide during

treatment of the HDPE. The treatment is believed to have made the particles hydrophilic, hence

allowing them to adhere better to cement.

Anum and Job 119

Figure 5(a) Compressive Strength with Curing Period for M 25 Concrete

Figure 5(b) Compressive Strength with Curing Period for M50 Concrete

5. CONCLUSION

The following conclusions were drawn from the study of compressive strength characteristics

of concrete modified with treated high-density polyethylene. The rough and reduced particle

size with increased surface areas of the treated Pulverized High-Density Polyethylene as

revealed by SEM substantially improved the bonding of plastic to cementitious materials as

compared to the untreated samples.

Compressive strengths of all concrete specimens increased with curing age compared on the

basis of 90 days tested but decreased with the inclusion of Pulversised High-Density

Polyethylene with the least reduction of 19.09% (29.67 N/mm2) for Grade M25 while 16.04%

(45.32 N/mm2) for Grade M50 concrete.

The study has shown the benefits of pulverisation and chemical treatment of HDPE on

improving compressive strength properties of concrete, thus contributing to the body of

knowledge on the use of waste plastic concrete. The study empirically revealed that the


incorporation of 0.5% of HDPE by weight of cement gives the optimum strength improvement

for both Grade M25 and M50 concretes. The study has thus provided a guild to practitioners on

the use of High-Density Polyethylene in concrete for construction purposes. Based on the

findings of this study, it was recommended that 0.5% by weight of cement of treated pulverised

HDPE could be used as an admixture in normal and high strengths concretes without

compromising their compressive strengths.

This study limited the treatment of High-Density Polyethylene with only hydrogen peroxide.

Therefore, the research suggested future studies to look at the effects of using other oxidizing

chemicals for the treatment of High-Density Polyethylene. Similarly, the effects of treatment on

HDPE should also be investigated.

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COMPRESSIVE STRENGTH CHARACTERISTICS OF CONCRETE …